1. Field of the Invention
The present invention relates to an electrical connector housing used in automobiles. More particularly, the invention concerns bus bars used as internal circuits of the electrical connector housing. According to the invention, these bus bars are manufactured in a simple way, without recourse to a traditional method of stamping out circuit-shaped bus bar through a die.
2. Description of Background Information
The internal circuits of an electrical connector housing, such as a junction box used in automobiles, mainly make use of bus bars formed in circuit shapes. Such bus bars are stamped out from an electrically conductive metal sheet through a die. Besides the approach involving the use of bus bars, there exists another approach in which electrical cables are wired along circuitry on an insulator sheet, and are then press-connected through press-fit terminals by clamping (press-connection system). These two approaches may also be applied in combination.
However, recent developments in this field have brought about an increase in the number of electrical parts equipped and the number of circuits used in an electrical connector housing. The shape of insulator sheets used for cable wiring has also become more complex than in the past. Under such circumstances, if the press-connection system is used for wiring the internal circuits, more time and costs will be consumed for cable wiring and insulator-sheet manufacturing.
If bus bars are used for internal circuits, respective stamping dies have to be prepared for the different circuits produced. Under such conditions, circuit changes will not be responded to as quickly as desired. In addition, the die manufacturing processes incur high costs. Moreover, as the stamping process leaves important portions of unused sheet, the product yield of a conductive metal sheet will be considerably low. As a result, the manufacturing cost of the bus bars is relatively high. Further, as the number of circuits used in an electrical connector housing increases, the number of bus bars required also increases. Nowadays, seven or eight pieces of bus bars must sometimes be superposed in multiple layers. At the same time, corresponding insulator sheets must be interposed therebetween. Such a structural feature therefore tends to increase the total costs.
In view of the above problem, a circuit sheet 2 shown in FIGS. 1A and 1B has been used to implement an electrical connector housing (Japanese Patent Application published under SHO 56-130989). According to the disclosure in this patent application, a conductive metal sheet is stamped out so as to yield cut-off portions 3a and a checkered conductive sheet 3. Two faces of the checkered conductive sheet 3 are then laminated with insulator sheets 1a and 1b. Thereafter, unnecessary circuit paths 3b are cut off so as to form a desired circuit. The checkered conductive sheet 3 is then encircled by electrical cables, and led to external circuits.
As a circuit is formed by cutting off unnecessary circuit paths 3b, the circuit can be modified quickly. However, as checkered circuits are formed by stamping, i.e. by removing many cut-off portions 3a, the product yield from the conductive metal sheet is rather low. Further, an electrical connector housing, e.g. an automobile junction box, requires many circuits such as power-source circuits located upstream of the fuses, load circuits located downstream of the fuses, and circuits unconnected to the fuses. Consequently, the number of bus bar layers becomes large, thereby increasing production costs.
In view of the above, a first object of the invention is to provide an electrical connector housing in which circuits can be formed by unit blocks. A second object of the invention is to reduce the costs of forming internal circuits. A third object of the invention is to be able to respond quickly to changes of internal circuits.
To this end, there is provided an electrical connector housing including at least one housing case including one or more outwardly projecting connector-fitting portions, fuse-fitting portions and/or relay-fitting portions. The at least one housing case includes a plurality of circuit blocks, each of the circuit blocks including at least one X-directional bus bar layer and at least one Y-directional bus bar layer superposed thereon. The X-directional and Y-directional bus bar layers contain strip-shaped bus bars and an insulator sheet. The strip-shaped bus bars are arranged in parallel at a given interval, respectively in X direction and Y direction perpendicular thereto. The plurality of circuit blocks are then superposed on one another with an insulator plate interposed therebetween, such that the bus bars arranged in the X and Y directions from cross points. The cross points are then electrically connected to each other at desired cross points so as to form branched circuits, while the bus bars in the X and Y directions have bent end portions to form tabs, and the tabs are contained in the connector-fitting portions, fuse-fitting portions and/or relay-fitting portions.
In the bus bars arranged respectively in the X and Y directions, required circuits are formed by removing unnecessary paths in the circuits. In such a structure, strip-shaped bus bars having a given size can be used for both the X and Y directions. The bus bars can thus be prepared uniformly, and production costs can be reduced.
As the electrically conducting portions constituting the internal circuits are all made of strip-shaped bus bars, a common material can be used. The efficiency in the use of material and yield are thus improved. Further, the stamping process using dies, hitherto necessary for making bus bars, can be obviated, thereby greatly reducing circuit-production costs.
The strip-shaped bus bars are arranged in parallel, at a given pitch, in X and Y directions. This pitch can be chosen such as to correspond to the pitch between the terminal holes for the connector, fuse or relay. For instance, some of the bus bars arranged in parallel in the X direction are disposed so as to correspond to the pitch between the fuses, while the remainder thereof are disposed so as to correspond to the pitch between the relays. Likewise, some of the bus bars arranged in parallel in the Y direction, perpendicular to the X direction, are disposed so as to correspond to a small pitch between the connector terminal holes, while some other bus bars are disposed so as to correspond to a median pitch, and the remainder of the bus bars are disposed so as to correspond to a large pitch.
When the bus bars are arranged crosswise in the X and Y directions at a pitch corresponding to that between the terminal holes of the connectors, fuses and relays, the tabs formed by folding these bus bars can be connected to the connectors, fuses and/or relays directly.
When the X-directional layer and the Y-directional layer, respectively including strip-shaped bus bars, are superposed to form more than two layers, desired circuit blocks can be formed preliminarily in a simple way. By changing the combination of blocks or combinations inside a block, circuits can be changed easily. Further, when the circuits are formed by blocks, the strip-shaped bus bars can be designed to have the same width, as a function of required current intensities. The circuits can thus be formed simply as a unit of block. Furthermore, the circuits can be assembled by blocks in the electrical connector housing, so that the assembly efficiency can be improved.
The plurality of circuit blocks include one or more power-source circuit blocks located upstream of the fuses, one or more load-circuit blocks located downstream of the fuses and one or more splice-circuit blocks unconnected to the fuses. Further, the power-source circuit block(s), load-circuit block(s) and splice-circuit block(s) has (have), respectively, a broad width suitable for high current circuits, a medium width suitable for medium current circuit, and a narrow width suitable for weak or mini current circuit.
Accordingly, a power-source-circuit block, a load-circuit block and a splice-circuit block are formed by combining the X-directional bus bar layer and the Y-directional bus bar layer. A required circuit can thus be formed simply by assembling these blocks.
The bus bars have first and second faces laminated with a respective insulator resin sheet. The bus bars, arranged respectively in the X and Y directions, are connected to each other by riveting or welding at the cross points. The bus bars contained in different blocks are then connected to one another by interposing a pin with two edges in a position perpendicular to the bus bars, and welding the two edges thereto.
As the bus bars are coated with insulator resins, there is no need to interpose an insulator plate between the X-directional and the Y-directional bus bar layers. Accordingly, when the blocks are mounted in the electrical connector housing, only the zones between the blocks are to be interposed with an insulator plate. Compared to the past practice in which all the bus bar layers are interposed by an insulator plate, the present invention enables the number of insulator plates to be reduced. As a result, costs are reduced, and the electrical connector housing can be miniaturized.
In another aspect of the present invention, a method of making an electrical connector housing is provided. The method includes providing at least one housing case including at least one of outwardly projecting connector-fitting portions, fuse-fitting portions and relay-fitting portions; the at least one housing case comprising a plurality of circuit blocks, providing each of the circuit block with at least one X-directional bus bar layer and at least one Y-directional bus bar layer superposed thereon, the X-directional and Y-directional bus bar layers containing strip-shaped bus bars and an insulator sheet. The method also includes arranging the strip-shaped bus bars in parallel at a given interval, respectively in an X direction and in a Y direction perpendicular thereto, superposing the plurality of circuit blocks on one another and interposing an insulator plate therebetween such that the bus bars arranged in the X and Y directions form cross points, and electrically connecting selected ones of the cross points to each other to form branched circuits. The method may further include bending end portions of the bus bars in the X and Y directions to form tabs, and inserting the tabs into respective ones of the connector-fitting portions, fuse-fitting and relay-fitting portions.
In a further aspect of the invention, the method includes providing the plurality of circuit blocks to include at least one power-source circuit block located upstream of fuses, at least one load-circuit block located downstream of the fuses and at least one splice-circuit block unconnected to the fuses, and providing the power-source circuit blocks, load-circuit blocks and splice-circuit blocks with, respectively, a broad width suitable for high current circuitry, a medium width suitable for medium current circuitry, and a narrow width suitable for weak or mini current circuitry.
According to other aspects of the present invention, the method may further include laminating first and second faces of each the bus bar with an insulator resin sheet, connecting the bus bars arranged respectively in the X and Y directions to each other by at least one of riveting and welding at the cross points, and connecting the bus bars contained in different blocks to one another by interposition of a pin with two edges in a position perpendicular to the bus bars, and welding the two edges thereto.